The 2008 ice storm, the floods of Tropical Storm Irene, a freak October snow storm, the Springfield tornado and planning for last summer’s Hurricane Sandy — all have sparked interest in local towns for a regional sheltering plan that might be needed in getting through the next emergency.

Last month, after two years of work, the Franklin County Regional Shelter Plan was completed and a draft agreement about how the plan would work was sent to all Franklin County towns. Towns’ officials are now reviewing the plan and considering whether to take part in it. This plan is an addendum to the “Western Massachusetts Intergovernmental Emergency Mutual Aid Agreement,” which all Franklin towns have already signed.

This additional agreement asks participating towns to work together to coordinate and operate regional shelters that would provide assistance to displaced disaster victims. It asks towns to “pay their fair share of operational costs,” and to collaborate to provide trained personnel, equipment and/or a shelter facility.

The plan is similar to existing mutual-aid agreements among fire and police departments in different towns. But the cost-sharing and running of regional shelters — housed in one town but available for use by more than one town — is a complicated process, said Patricia A. Smith, senior land use planner for the Franklin Regional Council of Governments. The costs incurred by the shelter building owner, including heat, electricity, janitorial services and nursing staff, will be included in the invoices sent to participating communities.

The addendum is to remain in effect for up to 25 years, unless terminated earlier by any of the communities. Any town can withdraw after giving the other participating towns 60 days’ notice in writing.

The 339-page plan lists five primary sites for regional shelters: the Orange Armory, the Colrain Center Elementary School, the Franklin County Technical School in Turners Falls, the Greenfield Middle School and the Mohawk Trail Regional High School, in Buckland.

Next, it lists 14 locations to serve as “back up” regional shelter facilities, which might be opened to accept an overflow of people who could not be accommodated by a primary shelter, or as an alternate location if the primary shelter site is in the emergency area. The secondary sites range from the Athol-Orange Elks Club to schools in Bernardston, Conway, Orange, Deerfield, Northfield, Ashfield, Gill, Shutesbury, Sunderland and Turners Falls.

A third subset, classified as “unique,” includes such locations as the Cowell Gymnasium in Shelburne, Greenfield High School, the Heath Fairgrounds and the Rowe Camp and Conference Center.

“The ‘unique’ are a really interesting group,” said Smith. “They would not generally be used, except in very unique circumstances. For instance, in an earthquake, where buildings are falling down we might have to put up tent cities. That’s why fairgrounds and the Orange Airport are among those places. The primary and backups are the more traditional places.”

Because of Franklin County’s topography and crisscossing of many rivers, the five primary shelters were configured so that residents throughout the county could reach a regional shelter without having to cross a river, said Smith.

The plan gives out detailed information about each facility, including who to contact to use it as a shelter, its distance to an emergency evacuation route, whether it’s an American Red Cross Shelter, whether pets would be accepted there, handicapped-accessibility, and each site’s relative strengths and limitations.

The plan also includes the building layout and which parts of the building could be used for a shelter and which parts would be out of bounds.

The plan for shared costs asks the host community to pay for expenses to operate the regional shelter, and then seek reimbursement from the other participating towns that requested sheltering assistance. The portion of costs that each town pays would be based on the overall percentage of residents from each town, calculated for each day the shelter was in operation. If a participating town provides staff to operate the shelter, the town’s costs would be reduced by the value of those services.

The plan lists the emergency management directors for each town, along with their contact information.

“The regional shelter planning process in Franklin County began with a Sheltering Summit in March 2012 in the Montague Public Safety Complex,” said Smith. She said nearly 60 people attended, including local board of health officials, emergency management directors, firefighters, Medical Reserve Corps members, housing officials, school officials, religious leaders, transportation representatives, and members of the Shelburne Control Dispatch Center and the state Emergency Management Agency (MEMA).

“At that meeting, the focus was to develop a list of potential primary sites and multiple backups,” she said. “Many of the shelters are schools, so regional school districts were also involved.

Besides paying for development of the regional shelter plan, the Western Region Homeland Security Advisory Council will also provide caches of shelter equipment that are to go into the regional shelters. These would include such things as cots and blankets, sanitation supplies, wheelchairs or even generators.

This 15-member volunteer council is charged by the Executive Office of Public Safety and Security to administer and coordinate the State Homeland Security Grant for the four counties of Western Massachusetts: Berkshire, Franklin, Hampshire and Hampden. These activities are regional and intended to enhance enable the region to prevent, protect against, mitigate, respond to and recover from the threats and hazards that pose the greatest risks.

In an earlier round of funding, said Smith, the council purchased “shelter trailers” that are filled with shelter equipment that can travel to one of the sites. Smith said one of these trailers is now stored on the grounds of the Franklin County jail; another is in Buckland. “These are regional assets, so that anyone that needs them can call for it,” she said.

Smith said the plan was developed by FRCOG over the last couple of years, with input from the Franklin County Regional Emergency Planning Committee. It was based on a model developed by the Berkshire Regional Planning Commission, but tailored for Franklin County.

“What we are hoping is that all the towns will participate,” said Smith. “All the towns have signed the Emergency Mutual Aid Agreement. But the specifics of what happens at a shelter is different from sharing trucks — there are different cost-sharing considerations.”

Smith said that spelling out how each shelter is to be run and who pays for what may help eliminate future arguments.